GB2241973A

GB2241973A - Waterproofing of tunnel lining

Info

Publication number: GB2241973A
Application number: GB9005911A
Authority: GB
Inventors: Samuel Bailey Hart Mitchell; Alan Williams Gimbert
Original assignee: Costain Building Products Ltd
Current assignee: Costain Building Products Ltd
Priority date: 1990-03-16
Filing date: 1990-03-16
Publication date: 1991-09-18
Anticipated expiration: 2010-03-16
Also published as: GB9005911D0; GB2241973B

Abstract

This disclosure relates to a arcuate precast concrete tunnel lining segment (10) having end faces (11) and circumferentially extending side faces (12). The end faces (11) have relatively shallow grooves (13) in which relatively thin sealing strips formed from a water swellable material, such as hydrophilic rubber (14), are mounted to project from the faces for sealing engagement with adjacent corresponding faces of other segments. The circumferentially extending side faces (12) of the segment are formed with slightly deeper grooves (15) containing correspondingly thicker gaskets formed from a rubber or neoprene (16) to project further from the side faces and to seal with corresponding faces of adjacent segments. The thicker gaskets (16) projecting further from the side faces allow a greater tolerance at the circle joints of the segments to accommodate ground movement and building tolerances. <IMAGE>

Description

WATERPROOFING OF TUNNEL LINING This invention relates to tunnel/shaft linings and is particulary although not exclusively applicable to tunnel/shaft linings formed from pre-cast concrete segments.

In locations where tunnel/shaft linings are erected in water bearing ground and it is necessary to seal the lining to prevent the ingress of moisture. Such linings can be sealed by injecting a layer of grout into the ground around the lining and/or grouting between adjacent segments. It has also been proposed to insert resilient sealing strips between the abutting faces of adjacent segments in a tunnel or shaft lining and water swellable rubbers have also been devised for sealing between components such as tunnel/shaft lining elements. European Patent Publication Nos. 0059062 and 0147764 disclose examples of such water swellable rubbers.

This invention provides a tunnel/shaft lining comprising a plurality of rings each consisting of a plurality of arcuate segments, abutting edges of segments around each ring having relatively shallow opposing grooves from which relatively shallow sealing strips of a water swellable material project to interengage each other and edges of adjacent segments in each ring having opposing relatively deeper grooves from which relatively thick resilient sealing strips project to interengage each other and to accomodate building tolerances and movement between adjacent rings.

The water swellable material is preferably a hydrophilic rubber and the resilient sealing strip may be formed from an E.P.D.M. rubber or neoprene.

At each corner of a segment the water swellable sealing strip extending along one edge of the segment abuts with the resilient sealing strip extending along the adjacent edge of the segment and the water swellable sealing strip and the resilient sealing strip may be bonded together at each corner of the segment.

More specifically the water swelling sealing strip may extend across an end of the resilient strip and may be bonded thereto.

The following is a description of some specific embodiments of the inveniton, reference being made to the accompanying drawings in which: Figure 1 is a diagramatic view of an end part of an arcuate tunnel lining segment incorporating sealing strips on the edge faces of the segments; and Figure 2 is a detailed view of the seal arrangement of Figure 1.

Referring firstly to Figure 1 of the drawings there is shown a part of an arcuate pre-cast concrete tunnel lining segment 10 having end faces 11 (only one of which is shown) and circumferentially extending side faces 12. In erecting a tunnel lining, a plurality of the arcuate segments 10 are located in rings with adjacent end faces of the segments in abuttment and may be secured together by fastening devices (not shown). The circumferential side faces 12 of the segments are located in abuttment with the corresponding side faces of a 'previously erected ring and again the segments of the newly erected ring may be secured to the segments of the previously erected ring using fastening devices which are not shown.

The abuttment between the end faces 11 of an adjacent pair of segments is known as the "cross-joint" and both of the end faces 11 of the segment at the cross-joint are formed with relatively shallow grooves 13 extending along the lengths of the faces 11. Relatively thin sealing strips formed from a hydrophilic rubber 14 are mounted in the grooves to project from the grooves and to abut one another to form a waterproof seal between the end faces of the segments. By minimising the width of the groove 13 at the cross-joint the maximum load bearing area of the end face 11 is preserved to spread the circumferential loads imposed on the ring. If the ground around the tunnel lining ring is wet, the water swellable sealing material absorbs moisture and swells to increase the sealing pressure between the seals and thereby further resist passage of moisture between the seals.

Both circumferentially extending side faces 12 of the segment are formed with slightly deeper grooves 15 extending around the faces from which correspondingly thicker gaskets formed from an E.P.D.M. rubber 16 to project correspondingly further from the side faces. The side faces 12 of the segment abut with the similarly formed side faces of adjacent segments forming what is known as the "circle joints" and the rubber sealing strips abut the sealing strips projecting from the adjacent side face to form seals at the cross-joint. By making the strips 16 somewhat thicker to project further from the side faces, a greater building tolerance is catered for at the circle joint than at the cross-joint to accomodate both movement in the ground and building tolerances.

The sealing strips 14 and 16 may or may not overlap at the corner of the segment where they meet or a special corner section may be used for jointing at the corner. In the arrangement shown in Figure 2, a section of the sealing strip t4 is illustrated and it will be seen that raised ribs 17 may be formed on the strip to engage the adjacent seal on the adjacent segement. The sealing strip 16 illustrated has a hexagonal cross-section (although other shapes may also be useful) and may be both wider as well as considerably deeper than sealing strip 12 to project further from the face of the segment in which it is mounted. The sealing strip 14 overlaps the ends of the sealing strip 16 as can be seen and is bonded to the strip 16 by a cyanoacrylate adhesive. Any void holes in the cross-section of the sealing strip 16 are plugged before bonding.

In a further construction preformed right angled corner pieces of resilient sealing material are provided for each of the corners of the segment to interconnect the sealing strips 14 and 16 which are bonded to the corner pieces.

Thus the invention provides a system for waterproofing segmental pre-cast concrete tunnel and shaft linings and other water or liquid retaining structures with the horizontal joint structure using one sealing material and the vertical joints using another form of sealing material. In the case of a tunnel lining, the water proofing material in the horizontal joints is a hydrophilic rubber which expands when in contact with water whereas in the vertical joints the material is an E.P.D.M. rubber or neoprene or other material which is not hydrophilic.

The hydrophilic and non-hydrophilic materials may or may not overlap each other where they meet or a special corner section may be used for jointing them.

The benefits of the arrangement are to ensure a minimal loss of cross-section area to the horizontal joint where the maximum load bearing area is of importance by using a relatively small section of hydrophilic rubber seal whilst retaining maximum flexibility of the vertical joint to accomodate movement or building tolerances by using a relatively larger section of E.P.D.M. or other non-hydrophilic rubber section. The hydrophilic rubber section requires a smaller groove size than for example E.P.D.M.

The vertical joint or joints (horizontal for shafts) would be fitted with an E.P.D.M. or other such type of non-hydrophilic material as previously described to maintain maximum flexibility of the joint position where loss of cross-sectional area may be of less importance.

Claims

CLAIMS:

1. A tunnel/shaft lining comprising a plurality of rings each consisting of a plurality of arcuate segments, abutting edges of segments around each ring having relatively shallow opposing grooves from which relatively shallow sealing strips of a water swellable material project to interengage each other and edges of adjacent segments in each ring having opposing relatively deeper grooves from which relatively thick resilient sealing strips project to interengage each other and to accomodate building tolerances and movement between adjacent rings.

2. A tunnel/shaft lining as claimed in Claim 1, wherein the water swellable material is a hydrophilic rubber.

3. A tunnel/shaft lining as claimed in Claim 1 or Claim 2, wherein the resilient sealing strips are formed from an E.P.D.M. rubber or neoprene.

4. A tunnel/shaft lining as claimed in any of the preceding claims wherein at each corner of a segment the water swellable sealing strip extending along one edge of the segment abuts with the resilient sealing strip extending along the adjacent edge of the segment.

5. A tunnel/shaft lining as claimed in Claim 4, wherein the water swellable sealing strip and the resilient sealing strip are bonded together at each corner of the segment.

6. A tunnel/shaft lining as claimed in Claim 5 wherein at each corner of the segment the water swelling sealing strip extends across an end of the resilient strip and is bonded thereto.

7. A tunnel/shaft lining as claimed in any of Claims 1 to 3, wherein the water swellable strip and the sealing strip are joined by preformed corner pieces of resilient sealing material at each corner of the segment.

8. A tunnel lining substantially described with reference to and illustrated in Figures 1 and 2 of the accompanying drawings.